encoding: OBufferStream code style corrections

refs #3727

Change-Id: I501d16649b8079f58895b8f9350a4d5ea5fedb9a
diff --git a/src/encoding/buffer-stream.cpp b/src/encoding/buffer-stream.cpp
new file mode 100644
index 0000000..e60ba77
--- /dev/null
+++ b/src/encoding/buffer-stream.cpp
@@ -0,0 +1,55 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2016 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#include "buffer-stream.hpp"
+
+namespace ndn {
+namespace detail {
+
+BufferAppendDevice::BufferAppendDevice(Buffer& container)
+  : m_container(container)
+{
+}
+
+std::streamsize
+BufferAppendDevice::write(const char_type* s, std::streamsize n)
+{
+  std::copy(s, s + n, std::back_inserter(m_container));
+  return n;
+}
+
+} // namespace detail
+
+OBufferStream::OBufferStream()
+  : m_buffer(make_shared<Buffer>())
+  , m_device(*m_buffer)
+{
+  open(m_device);
+}
+
+shared_ptr<Buffer>
+OBufferStream::buf()
+{
+  flush();
+  return m_buffer;
+}
+
+} // namespace ndn